Question: Multiply the following complex numbers: $({4+2i}) \cdot ({3})$
Answer: Complex numbers are multiplied like any two binomials. First use the distributive property: $ ({4+2i}) \cdot ({3}) = $ $ ({4} \cdot {3}) + ({4} \cdot {0}i) + ({2}i \cdot {3}) + ({2}i \cdot {0}i) $ Then simplify the terms: $ (12) + (0i) + (6i) + (0 \cdot i^2) $ Imaginary unit multiples can be grouped together. $ 12 + (0 + 6)i + 0i^2 $ After we plug in $i^2 = -1$ , the result becomes $ 12 + (0 + 6)i - 0 $ The result is simplified: $ (12 - 0) + (6i) = 12+6i $